A heat exchanger for cooling particulate matter from a high-temperature industrial process or warming material from a cryogenic process is disclosed. The heat exchanger comprises a structure comprising a rectangular frame, piping that is supported by the rectangular frame and completes at least one circumference around the rectangular frame, and a fan. The piping is supported to the frame on a series of moving supports. The piping comprises an inlet end and an outlet end, and the piping contains external cooling fins. The structure is sealed except for where the finned piping is located.